Non-contact type pile cutting apparatus using waterjet and cutting method thereof

ABSTRACT

The present disclosure relates to a non-contact type pile cutting apparatus using a waterjet, particularly to a pile cutting apparatus entering the inside for cutting a pile including: a body that has a pipe form and is put into an inside of the pile; a gripper unit that is provided at an outer side of the body and fixes the body to the pile when the pile cutting apparatus has reached a cutting position of the pile; a waterjet unit that is provided at one side of the body and fixed by the gripper unit, and then sprays an abrasive mixture in which an abrasive and a fluid are mixed, toward the pile in a high pressure; a rotation unit that rotates the waterjet unit around a central axis of the body; a feed line that feeds the abrasive mixture in which the fluid and the abrasive of a set ratio are mixed, to the waterjet unit from the outside; a feed unit that controls a feed pressure of the abrasive mixture fed through the feed line; and a nozzle driving unit that controls a position of the waterjet unit.

BACKGROUND Technical Field

The present disclosure relates to a non-contact type pile cuttingapparatus using a waterjet and methods for operating and controlling thesame.

Related Art

An offshore jacket structure is installed integrally with a pilepenetrated into the seabed. Namely, the offshore jacket structure isbuilt by seating jacket legs belonging to the lower structure of theoffshore jacket structure on the seabed, inserting a jacket pile into ajacket leg so as to penetrate the lower part of the jacket pile into theseabed, fixing the jacket pile and the jacket leg by grouting betweenthem, and filling the inside of the jacket pile with infilled concrete.At this time, when a hard support layer such as rock bed exists,following drilling, is inserted an anchor pile (pin pile), followed bygrouting between the jacket pile and the anchor pile for fixation, andtreating infilled concrete.

The demolition process of an existing offshore jacket structure includesdemolishing the oil well or electrical facility connected to the jacketor seabed and then the topside facility of the offshore jacketstructure, following by the remaining penetrated jacket piles.

It is required to remove the jacket pile installed on the seabed to adepth of 3-5 m from the seabed according to international standards.

When installing the jacket structure, the jacket pile inside the jacketleg is penetrated into the seabed, and then the inside of the pile istreated with infilled concrete. Since it is difficult to penetrate thejacket pile into the hard support layer by pile driving, it is generalto drill the inside of the jacket pile and installing an anchor pile,followed by grouting between the anchor pile and the jacket pile andtreating the rest with infilled concrete.

Further, a waterjet cutting apparatus is an ultraprecise processingapparatus that processes or cuts a workpiece by spraying high pressurewater including an abrasive in the form of a particle thereto.

A waterjet or an abrasive waterjet system is used to cut a wide range ofmaterials including stone, glass, ceramics and metal. In the typicalwaterjet system, high pressure water flows through a cutting head with anozzle that directs a cutting jet to the workpiece. The waterjet systemabsorbs or feeds an abrasive medium into or to a high pressure waterjet,so as to form a high pressure abrasive waterjet. Then, the cutting headmay be controllably moved across the workpiece so as to cutting the sameas desired, or the workpiece may be controllably moved to beneath thewaterjet or the abrasive waterjet. For example, a system for generatinga high pressure waterjet such as TM 5 axis waterjet system manufacturedby Flow International Corporation are currently available. Anotherexample of Mach 4 waterjet system is shown and described in U.S. Pat.No. 5,643,058 of Flow, which is incorporated herein by reference intheir entirety.

When applying the abrasive waterjet cutting system to cut penetrationpiles, it is difficult to determine as to whether seabed penetrationpiles are cut or not, whether the piles are penetrated through awaterjet or not, etc. Thus, there is a problem in monitoring the entirecutting process.

SUMMARY Technical Problem

Therefore, the present disclosure is contrived to solve conventionalproblems as described above. According to the embodiment of the presentdisclosure, aimed is to provide a non-contact type pile cuttingapparatus using a waterjet and methods for operating and controlling thesame, wherein an abrasive and a fluid mixed at a set mixing ratio arefed in a mixture from the outside without any separate high pressurefluid and abrasive feed lines, allowing simplifying a feed line, and thepile cutting apparatus is furnished with a gripper unit, allowingfacilitating fixation and release thereof inside a penetration pile.

According to the embodiment of the present disclosure, aimed is toprovide a non-contact type pile cutting apparatus using a waterjet andmethods for operating and controlling the same, wherein a rotation unitis controlled by identifying as to whether a penetration pile ispenetrated by a waterjet or not, based on the data measured from a soundsensor and a vibration sensor during the cutting process, allowingremote-monitoring the cutting process without introducing any equipmentsuch as a vision sensor.

Further, according to the embodiment of the present disclosure, aimed isto provide a non-contact type pile cutting apparatus using a waterjetand methods for operating and controlling the same, wherein a waterjetunit includes a guide portion, a nozzle moving unit and a nozzle settingunit, allowing precisely setting a nozzle portion prior to high pressurespaying of the waterjet.

Technical Solution

The present disclosure aims to achieve a non-contact type pile cuttingapparatus using a waterjet, as a pile cutting apparatus entering theinside for cutting a pile, includes: a body that has a pipe form and isput into an inside of the pile; a gripper unit that is provided at anouter side of the body and fixes the body to the pile when the pilecutting apparatus has reached a cutting position of the pile; a waterjetunit that is provided at one side of the body and fixed by the gripperunit, and then sprays an abrasive mixture in which an abrasive and afluid are mixed, toward the pile in a high pressure; a rotation unitthat rotates the waterjet unit around a central axis of the body; a feedline that feeds the abrasive mixture in which the fluid and the abrasiveof a set ratio are mixed, to the waterjet unit from the outside; a feedunit that controls a feed pressure of the abrasive mixture fed throughthe feed line; and a nozzle driving unit that controls a position of thewaterjet unit.

The non-contact type pile cutting apparatus using a waterjet furtherincludes: a casing which is connected to a lower part of the body, andin which an opening provided as a passage where a nozzle portion of thewaterjet unit is protruded and inserted is formed, wherein the rotationunit is installed inside the casing, and the waterjet unit includes: anozzle housing in which the nozzle portion that is connected to the feedline and sprays the abrasive mixture toward the pile in a high pressureis provided; a nozzle moving unit that moves the nozzle portion in aradial direction of the pile in the nozzle housing; and a guide portionwhich is provided at one side of the nozzle housing and is in contact ina state that the nozzle portion is being moved toward an inner surfaceof the pile by the nozzle moving unit, thus maintaining a distancebetween an end of the nozzle portion and the inner surface of the pilewithin a set range.

Further, non-contact type pile cutting apparatus using a waterjetfurther includes: a nozzle setting unit that performs rotation from aninner side of to an outer side of the casing of the nozzle housing, orreversely, wherein the guide portion includes: a rotation roller that isspaced apart from the nozzle portion at a predetermined interval in alength direction, and is provided at a position protruded toward anouter side of the nozzle portion; a tension unit that gives an elasticforce to the rotation roller in an outer radial direction while allowingmoving the rotation roller in a radial direction; and a tensiondetection portion that measures the elastic force of the tension unit inreal time, and a control portion controls the nozzle moving unit so asto fix a radial direction position of the nozzle portion when theelastic force detected from the tension detection portion has reached aset range.

The gripper unit has a link structure and includes: a plurality ofgripper members that is pressurized to and contacted with an inner sideof the pile, when performing fixation to the body; and a link drivingportion that moves the gripper member toward the pile when performingfixation, while moving the gripper member toward the body whenperforming release.

Further, a plurality of protrusions is installed on an outer surface ofthe gripper member. The link driving portion includes: a cylindricalshaped movable housing that moves up and downwardly while covering anouter surface of the body; and a driving link that is installed in aradial direction of the movable housing and drives the movable housingup and downwardly. The link structure includes: a connection link ofwhich an inner end is hinge-connected with the driving link, and ofwhich an outer end is hinge-connected to one side of the gripper member;an upper link of which an inner end is hinge-connected with an upperconnection end installed to one side of an upper outer surface of thebody, and of which an outer end is hinge-connected with an upper side ofthe gripper member; and a lower link of which an inner end ishinge-connected with an lower connection end installed to one side of alower outer surface of the body, and of which an outer end ishinge-connected with a lower side of the gripper member. The grippermember is spread out toward the pile when the movable housing has beenmoved to a top part by the driving link, while being folded when themovable housing has been moved to a bottom part.

The non-contact type pile cutting apparatus using a waterjet furtherincludes: a determination portion that includes a sound sensor providedat the nozzle housing and measuring sound data during work, and avibration sensor measuring a vibration state of the nozzle housing,wherein the determination portion determines that the pile has been cutwhen a sound signal and a vibration value measured from the sound sensorand the vibration sensor are within set ranges.

Further, the non-contact type pile cutting apparatus using a waterjetfurther includes: database (DB) where stored are a pile thickness,ranges of sound data and vibration during cutting by the abrasivemixture according to materials, and ranges of sound data and vibrationfollowing penetration by the abrasive mixture, wherein the determinationportion determines as to whether the pile has been cut or not, based onranges of the sound data and vibration stored in the DB, and the controlportion moves the nozzle housing in a circumferential direction up to aset angle by driving the rotation unit when the determination portiondetermines that the pile has been penetrated by a waterjet.

Advantageous Effects

According to a non-contact type pile cutting apparatus using a waterjetand methods for operating and controlling the same in accordance withthe present disclosure, an abrasive and a fluid mixed at a set mixingratio is fed in a mixture from the outside without any separate highpressure fluid and abrasive feed lines, allowing simplifying a feedline, and the pile cutting apparatus is furnished with a gripper unit,allowing facilitating fixation/release thereof inside a penetrationpile.

According to a non-contact type pile cutting apparatus using a waterjetand methods for operating and controlling the same in accordance withthe present disclosure, a rotation unit is controlled by identifying asto whether a penetration pile is penetrated by a waterjet or not, basedon the data measured from a sound sensor and a vibration sensor duringthe cutting process, allowing remote-monitoring the cutting processwithout introducing any equipment such as a vision sensor.

Further, According to a non-contact type pile cutting apparatus using awaterjet and methods for operating and controlling the same inaccordance with the present disclosure, a waterjet unit includes a guideportion, a nozzle moving unit and a nozzle setting unit, allowingprecisely setting a nozzle portion prior to high pressure spaying of awaterjet.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a non-contact type pile cutting apparatus usinga waterjet when performing release according to an embodiment of thepresent disclosure,

FIG. 2 is a side view of a non-contact type pile cutting apparatus usinga waterjet when performing fixation according to an embodiment of thepresent disclosure,

FIG. 3 is a side view of a non-contact type pile cutting apparatus usinga waterjet according to an embodiment of the present disclosure,following setting-up,

FIG. 4 is a front view of a non-contact type pile cutting apparatususing a waterjet according to an embodiment of the present disclosure,following setting-up,

FIG. 5 is a perspective view of a non-contact type pile cuttingapparatus using a waterjet according to an embodiment of the presentdisclosure, following setting-up,

FIG. 6 is a side view of a non-contact type pile cutting apparatus usinga waterjet when performing fixation when performing release according toanother embodiment of the present disclosure,

FIG. 7 is a side view of a non-contact type pile cutting apparatus usinga waterjet when performing fixation according to another embodiment ofthe present disclosure,

FIG. 8 is a block view showing signal flow of a control portionaccording to an embodiment of the present disclosure,

FIG. 9 is a flowchart of a non-contact type pile cutting method using awaterjet according to an embodiment of the present disclosure,

FIG. 10 is a cross-sectional view of a nozzle portion according to anembodiment of the present disclosure,

FIG. 11 is a cross-sectional view of a nozzle portion having a structureof a double pipe according to an embodiment of the present disclosure,

FIG. 12 is a structural view of a feed unit according to an embodimentof the present disclosure, and

FIG. 13 is a cross-sectional view of a cooling unit according to anembodiment of the present disclosure.

REFERENCE NUMBERS

-   -   1: fee line 2: cooling unit 3: insulation frame 4: evaporator 5:        cooling chamber    -   10: body 20: gripper unit 21: gripper member 22: connection link    -   23: upper link 24: lower link 25: movable housing 26: driving        link 27: driving wheel    -   30: casing 31: opening 40: nozzle setting unit 50: waterjet unit    -   51: nozzle housing 52: nozzle moving unit 60: nozzle portion 61:        entry area    -   62: acceleration portion 63: focusing portion 64: exit chamfer        65: double pipe 66: compressed air outlet pipe    -   70: guide portion 71: rotation roller 72: tension unit 73:        tension detection portion 80: rotation unit    -   90: feed unit 91: fluid tank 92: high pressure pump 93: abrasive        tank 94: control valve    -   95: mixing valve    -   100: non-contact type pile cutting apparatus    -   110: control portion 111: sound sensor 112: vibration sensor        113: DB 120: determination portion

DETAILED DESCRIPTION Best Mode

Hereinafter, described are the structure and function of a non-contacttype pile cutting apparatus using a waterjet according to an embodimentof the present disclosure, and methods for operating and controlling thepile cutting apparatus.

FIG. 1 is a side view of a non-contact type pile cutting apparatus usinga waterjet when performing release according to an embodiment of thepresent disclosure. FIG. 2 is a side view of a non-contact type pilecutting apparatus using a waterjet when performing fixation according toan embodiment of the present disclosure.

Further, FIG. 3 is a side view of a non-contact type pile cuttingapparatus using a waterjet according to an embodiment of the presentdisclosure, following setting-up, FIG. 4 is a front view of anon-contact type pile cutting apparatus using a waterjet according to anembodiment of the present disclosure, following setting-up, and FIG. 5is a perspective view of a non-contact type pile cutting apparatus usinga waterjet according to an embodiment of the present disclosure,following setting-up.

Further, FIG. 6 is a side view of a non-contact type pile cuttingapparatus using a waterjet when performing fixation when performingrelease according to another embodiment of the present disclosure. FIG.7 is a side view of a non-contact type pile cutting apparatus using awaterjet when performing fixation according to another embodiment of thepresent disclosure. Further, FIG. 8 is a block view showing signal flowof a control portion according to an embodiment of the presentdisclosure,

Further, FIG. 9 is a flowchart of a non-contact type pile cutting methodusing a waterjet according to an embodiment of the present disclosure.

A non-contact type pile cutting apparatus using a waterjet 100 accordingto an embodiment of the present disclosure may be configured to includea body 10, a gripper unit 20, a waterjet unit 50, a rotation unit 80, afee line 1, a feed unit 90, a nozzle moving unit 52, a nozzle settingunit 40, etc., in general.

The body 10 is configured to be put into the inside of a penetrationpile that is an object to be cut. The gripper unit 20 is provided at anouter side of the body 10, and configured to fix the body 10 to thepenetration pile when the pile cutting apparatus 100 has reached to acutting position of the pile and to release a fixation between the pilecutting apparatus and the penetration pile following cutting the pile.

Further, the waterjet unit 50 is configured to be provided at one sideof a lower part of the body 10 and fixed by the gripper unit 20, andthen to spray an abrasive mixture in which an abrasive and a fluid aremixed, toward the pile in a high pressure.

The rotation unit 80 is configured to rotate the waterjet unit 50 arounda central axis of the body 10. The feed line 1 is configured to fee theabrasive mixture in which the fluid and the abrasive of a set ratio aremixed, to the waterjet unit 50 from the outside. The feed unit 90 isconfigured with a high pressure pump, etc. and to control a feedpressure of the abrasive mixture fed through the feed line 1.

Further, the nozzle moving unit 52 may be configured to fix the pilecutting apparatus by the gripper unit 20, and then to control a positionof the waterjet 50.

A casing 30 is connected to the lower part of the body 90. In the casing30, formed is an opening 31 provided as a passage where a nozzle portion60 of the waterjet unit 50 is protruded and inserted. Further, therotation unit 80 is installed inside the casing 30.

The waterjet unit 50 according to an embodiment of the presentdisclosure may be configured to include a nozzle housing 51, a nozzlemoving unit 52, a guide portion 70, a nozzle setting unit 40, etc.

The nozzle housing 51 has the nozzle portion 60 that is connected to thefeed line 1 and sprays the abrasive mixture toward the pile in a highpressure. The nozzle moving unit 52 is configured to move the nozzleportion 60 in a radial direction of the pile in the nozzle housing 51.The guide portion 70 is provided at one side of the nozzle housing 51,and is configured to be contact in contact in a state that the nozzleportion 60 is being moved toward an inner surface of the pile by nozzlemoving unit 52, thus maintaining a distance between an end of the nozzleportion 60 and the inner surface of the pile within a set range.

FIG. 10 is a cross-sectional view of a nozzle portion 60 according to anembodiment of the present disclosure. As shown in FIG. 10 , it is seenthat the nozzle portion 60 according to the present disclosure may beconfigured to include an entry area 61, a conical shaped accelerationportion 62, a focusing portion 63 and an exit chamfer 64.

Preferably, the nozzle portion 60 is an acceleration nozzle that has anexit with a smaller diameter that that of the entry area 61. This allowsconverting the pressure inside a stream to an ultrahigh-speed stream. Asforming an exit with a smaller diameter than that of a slurry stream ona nozzle entry, the effect thereof will be increased more.

Preferably, the nozzle portion 60 has the focusing portion 60 with auniform diameter at an external end thereof, and the conical shapedacceleration portion 62 in which a diameter between the entry area 61and the focusing portion 63 becomes decreased. This allows an outputstream to achieve both desired speed and direction. A cone angle of theacceleration portion 62 does not exceed 27°. Preferably, the cone angleis about 13.5°. This provides a good balance between effectiveacceleration and a non-turbulent flow maintained. Preferably, thefocusing portion 63 of the nozzle portion 60 has a ratio of length todiameter larger than 5:1, preferably a ratio of length to diameterlarger than about 10:1. Further, it is preferable that the ratio oflength to diameter is smaller than about 30:1.

The nozzle portion 60 is a mixing nozzle that has the accelerationnozzle 62 formed with a material harder than that of the focusingportion 63. The focusing portion 63 has a diameter that is the same asor smaller than the acceleration area with the smallest diameter so asto prevent introduction of turbulence. The exit includes the exitchamfer 64 with a cone angle of about 45°. This angle is sufficient toensure flow separation in the exit.

FIG. 11 is a cross-sectional view of a nozzle portion having a structureof a double pipe 65 according to an embodiment of the presentdisclosure. As shown in FIG. 11 , according to the present disclosure,the structure of the double pipe 65 may be configured to feed compressedair to an outer side of the nozzle portion, allowing a high pressureabrasive mixture to have a spiral current generation area.

In the structure, provided are an annular slit-typed compressed airoutlet pipe 66 that feeds compressed air to a nozzle outlet and a pointreduced inner wall surface that is toward the compressed air outlet pipe66 from this slit, and a Coanda spiral air flow generation area isformed by the annular slit and the point reduced inner surface. Further,in an outlet portion of an inner pipe are placed an annular slit forfeeding high pressure water and a point reduced inner wall surface thatis toward an outlet, thereby forming a Coanda spiral current generationarea of high pressure water.

According to an embodiment of the present disclosure, an abrasivemixture tank is provided. In the abrasive mixture tank, an abrasivemixture in which an abrasive and a fluid (water) are mixed at a setratio is stored and a high pressure abrasive mixture is fed to thewaterjet unit 50 through the feed line 1 by the feed unit 90.

FIG. 12 is a structural view of a feed unit according to an embodimentof the present disclosure. Further, as shown in FIG. 12 , the feed unit90 according to an embodiment of the present disclosure includes a fluidto be pumped, in a fluid tank 91, and the fluid flows to a high pressurepump 92 through a pipe. The high pressure pump 92 increases pressure.The part of the fluid flow from the high pressure pump 92 changes forflowing in the pipe and then flows to the inside of an flexible slurrycontrol valve 94 and a friction type abrasive tank 93 includingabrasive. In general, 10% fluidity is directed to the friction typeabrasive tank 93 by a flowing pipe and the flexible slurry control valve94. The fluidity may controls the fluid which the abrasive is used in toremain with stopping flowing. In an example of the estimated blockingtime, the flow in a reference line may modulate an abrasiveconcentration so as to provide as 18% fluid. In the present disclosure,it is matter to maintain a diamond abrasive according to theconcentrated fluid ratio, as much as the type of the diamond abrasivesuch as a container, Garnet, various kinds of silica, copper slag andsynthetic materials. Alternatively, Corundum is used. The slurry of thefluid (i.e. water) and the abrasive is maintained at sufficient velocitysue to the volume of the fluid directed to the friction type abrasivetank 93. The abrasive is mixed with the fluid flow of the high pressurepump 92 by performing mixing through an abrasive mixing valve 95. Themixing valve 95 generates jet effect, hereby further including a Venturithat generates vacuum assistance in drawing water. With the describedorientation, the abrasive mixture come out from the spray nozzle portion60 may achieve ultrasonic velocity.

FIG. 13 is a cross-sectional view of a cooling unit according to anembodiment of the present disclosure. Further, according to anembodiment of the present disclosure, the cooling unit may be furtherprovided at one side of the fee line 1. A cooling unit 2 may include aninsulation frame 3, an evaporator 4, a cooling chamber 5, etc. Further,a water temperature control unit may be installed which maintains thetemperature of an abrasive mixture by controlling a temperature sensordetecting the temperature of the abrasive mixture to be fed and acooling capability of the cooling unit according to the temperaturedetected from the temperature sensor. Cutability is improved by usingthe feature that the viscosity depends on the temperature, for example,by increasing viscosity by cooling an ultrahigh pressure abrasivemixture with the cooling unit.

The nozzle setting unit 40 may be included, which rotates the nozzlehousing from an inner side of to an outer side of the casing, orreversely. This nozzle setting unit 40 may be configured to include alink structure and a hydraulic cylinder for driving this link structure.

Further, the guide portion 70 may be configured to include a rotationroller 71 that is spaced apart from the nozzle portion 60 at apredetermined interval in a length direction, and is provided at aposition protruded toward an outer side of the nozzle portion 60; atension unit 72 that gives an elastic force to the rotation roller 71 inan outer radial direction while allowing moving the rotation roller 71in a radial direction; and a tension detection portion 73 that measuresthe elastic force of the tension unit 72 in real time.

Therefore, a control portion 110 controls the nozzle moving unit 52 soas to fix a radial direction position of the nozzle portion 60 when theelastic force detected from the tension detection portion 73 has reacheda set range.

Description of Embodiments

Hereinafter, described is a method for cutting a pile through anon-contact type pile cutting apparatus using a waterjet according to anembodiment of the present disclosure. Firstly, a pile cutting apparatusis put into the inside of a pile through a putting apparatus 51.

When the pile cutting apparatus has reached a cutting position of thepile S2, a control portion 110 operates a gripper unit 20 to fix thepile cutting apparatus 100 to the inside of the pile S3.

Hereinafter, described is the configuration of the gripper unit 20. Thegripper unit 20 has a link structure, and is configured to include aplurality of gripper members 21 that is pressurized to and contactedwith an inner side of the pile, when performing fixation to the body 10,and a link driving portion that moves the gripper member 21 toward thepile when performing fixation, while moving the gripper member 21 towardthe body 10 when performing release.

More particularly, a plurality of protrusions is installed on the outersurface of the gripper member 21. The link driving portion includes acylindrical shaped movable housing 25 that moves up and downwardly whilecovering an outer surface of the body 10 and a plurality of drivinglinks 26 that is installed in a radial direction of the movable housing25 and drives the movable housing 25 up and downwardly. Further, adriving wheel may be provided to the driving link 26, thus driving themovable housing 25 up and downwardly by driving of the driving wheel 27.

Further, the link structure is connected to the respective driving links26, and is configured to include a connection link 22, an upper link 23and a lower link 24. An inner end of the connection link 22 end ishinge-connected with the driving link 26 and an outer thereof ishinge-connected to one side of the gripper member 21. An inner end ofthe upper link 23 is hinge-connected with an upper connection endinstalled to one side of an upper outer surface of the body 10 and anouter end thereof is hinge-connected with an upper side of the grippermember 21. An inner end of the lower link 24 is hinge-connected with alower connection end installed to one side of a lower outer surface ofthe body 10 and an outer end thereof is hinge-connected with a lowerside of the gripper member 21.

Thus, it is seen that when the movable housing 25 has been moved to thetop part by the driving link, as shown in FIG. 2 and FIG. 7 , thegripper member 21 is spread out toward the pile. It is also seen thatwhen the movable housing 25 has been moved to the bottom part, as shownin FIG. 1 and FIG. 6 , the gripper member 21 is folded.

When the pile cutting apparatus 100 has been fixed to the pile by thegripper unit 20, a waterjet nozzle is protruded toward an outer side ofthe opening 31 by the nozzle setting unit 40. The nozzle portion 60 ofthe waterjet nozzle is moved close to the inner surface of the pile bythe nozzle moving unit 52.

That is, the nozzle moving unit 52 moves the nozzle housing 51 providedwith the nozzle portion 60 in a radical direction of the pile, and is incontact in a state that the nozzle portion is being moved toward aninner surface of the pile by the nozzle moving unit, thus maintaining adistance between an end of the nozzle portion and the inner surface ofthe pile within a set range S4. That is, as mentioned above, the guideportion 70 includes the rotation roller 71 that is provided at aposition protruded toward the outer side of the nozzle portion 60, thetension unit 72 that gives an elastic force to the rotation roller 71 inan outer radial direction while allowing moving the rotation roller 71in a radial direction, and the tension detection portion 73 thatmeasures the elastic force of the tension unit 72 in real time. Thecontrol portion 110 controls the nozzle moving unit 52 so as to fix aradial direction position of the nozzle portion 60, when the elasticforce detected from the tension detection portion has reached a setrange.

The abrasive mixture in which a fluid and an abrasive of a set ratio aremixed is fed to the feed line 1 with the waterjet unit 50 from theoutside by the feed unit 90 S5, and the abrasive mixture is sprayedtoward the pile in a high pressure from the nozzle portion 60 of thewaterjet unit 50, which is connected to the fee line 1 S6.

The rotation unit 80 rotates the waterjet unit 50 around a central axisof the body 10 to cut the pile.

Hereinafter, described is a method for controlling a cutting process bythe waterjet unit 50 according to an embodiment of the presentdisclosure.

The embodiment of the present disclosure may be configured to include asound sensor 111 provided to one side of the pile cutting apparatus 100and measuring sound data during work, and a vibration sensor 112measuring a vibration state of the nozzle housing 51.

A determination portion 120 determines that the pile has been penetratedwhen a sound signal and a vibration value measured from the sound sensor111 and the vibration sensor 112 are within set ranges. That is,generated is a difference between a sound signal in a state of notcutting and a sound signal received following pile penetration, during aspraying process, and the determination portion 120 determined as towhether the pile has been penetrated or not, based thereon S7.

Further, in database (DB) 113, are stored a pile thickness, ranges ofsound data and vibration during cutting by the abrasive mixtureaccording to materials, and ranges of sound data and vibration followingpenetration by the abrasive mixture. The determination portion 120determines as to whether the pile has been cut and penetrated or not ascomparing the measured sound signal to the ranges of sound data andvibration stored in the DB 113.

Further, the control portion 110 drives the rotation unit 80 to move thenozzle housing 51 in a circumferential direction up to a set angle whenthe determination portion 120 determines that the pile has beenpenetrated by the waterjet S9. That is, following spraying, it isdetermined as to whether the pile is penetrated or not. When it isdetermined that the pile has been penetrated, the waterjet unit 50 ismoved up to a certain angle. When a sound signal according topenetration is still received following the movement thereof, it isdetermined that pile cutting has been completed S8. When a sound signalin a range of non-penetration is received after the movement at acertain angle, the pile is cut and penetrated by driving the waterjet.This process is continued repeatedly until determining that the pilecutting has been completed.

When it is determined that the pile cutting has been completed, it isstopped to feed the abrasive mixture 510, and the fixation between thepile and the pile cutting apparatus 100 is released S11, followed bytaking the pile cutting apparatus out S12.

1. A non-contact type pile cutting apparatus using a waterjet, as a pilecutting apparatus entering the inside for cutting a pile, comprising: abody that has a pipe form and is put into an inside of the pile; agripper unit that is provided at an outer side of the body and fixes thebody to the pile when the cutting apparatus has reached a cuttingposition of the pile; a waterjet unit that is provided at one side ofthe body and fixed by the gripper unit, and then sprays an abrasivemixture in which an abrasive and a fluid are mixed, toward the pile in ahigh pressure; a rotation unit that rotates the waterjet unit around acentral axis of the body; a feed line that feeds the abrasive mixture inwhich the fluid and the abrasive of a set ratio are mixed, to thewaterjet unit from the outside; a feed unit that controls a feedpressure of the abrasive mixture fed through the feed line; and a nozzledriving unit that controls a position of the waterjet unit.
 2. Thenon-contact type pile cutting apparatus using a waterjet of claim 1,further comprising: a casing which is connected to a lower part of thebody, and in which an opening provided as a passage where a nozzleportion of the waterjet unit is protruded and inserted is formed,wherein the rotation unit is installed inside the casing, and thewaterjet unit comprises: a nozzle housing in which the nozzle portionthat is connected to the feed line and sprays the abrasive mixturetoward the pile in a high pressure is provided; a nozzle moving unitthat moves the nozzle portion in a radial direction of the pile in thenozzle housing; and a guide portion which is provided at one side of thenozzle housing and is in contact in a state that the nozzle portion isbeing moved toward an inner surface of the pile by the nozzle movingunit, thus maintaining a distance between an end of the nozzle portionand the inner surface of the pile within a set range.
 3. The non-contacttype pile cutting apparatus using a waterjet of claim 2, furthercomprising: a nozzle setting unit that performs rotation from an innerside of to an outer side of the casing of the nozzle housing, orreversely, wherein the guide portion comprises: a rotation roller thatis spaced apart from the nozzle portion at a predetermined interval in alength direction, and is provided at a position protruded toward anouter side of the nozzle portion; a tension unit that gives an elasticforce to the rotation roller in an outer radial direction while allowingmoving the rotation roller in a radial direction; and a tensiondetection portion that measures the elastic force of the tension unit inreal time, and a control portion controls the nozzle moving unit so asto fix a radial direction position of the nozzle portion when theelastic force detected from the tension detection portion has reached aset range.
 4. The non-contact type pile cutting apparatus using awaterjet of claim 1, wherein the gripper unit has a link structure andcomprises: a plurality of gripper members that is pressurized to andcontacted with an inner side of the pile, when performing fixation tothe body; and a link driving portion that moves the gripper membertoward the pile during fixation, while moving the gripper member towardthe body when performing release.
 5. The non-contact type pile cuttingapparatus using a waterjet of claim 4, wherein a plurality ofprotrusions is installed on an outer surface of the gripper member, thelink driving portion comprises: a cylindrical shaped movable housingthat moves up and downwardly while covering an outer surface of thebody; and a driving link that is installed in a radial direction of themovable housing and drives the movable housing up and downwardly, thelink structure comprises: a connection link of which an inner end ishinge-connected with the driving link, and of which an outer end ishinge-connected to one side of the gripper member; an upper link ofwhich an inner end is hinge-connected with an upper connection endinstalled to one side of an upper outer surface of the body, and ofwhich an outer end is hinge-connected with an upper side of the grippermember; and a lower link of which an inner end is hinge-connected withan lower connection end installed to one side of a lower outer surfaceof the body, and of which an outer end is hinge-connected with a lowerside of the gripper member, and the gripper member is spread out towardthe pile when the movable housing has been moved to a top part by thedriving link, while being folded when the movable housing has been movedto a bottom part.
 6. The non-contact type pile cutting apparatus using awaterjet of claim 5, further comprising: a determination portion thatcomprises a sound sensor provided at the nozzle housing and measuringsound data during work, and a vibration sensor measuring a vibrationstate of the nozzle housing, wherein the determination portiondetermines that the pile has been cut when a sound signal and avibration value measured from the sound sensor and the vibration sensorare within set ranges.
 7. The non-contact type pile cutting apparatususing a waterjet of claim 6, further comprising: database (DB) wherestored are a pile thickness, ranges of sound data and vibration duringcutting by the abrasive mixture according to materials, and ranges ofsound data and vibration following penetration by the abrasive mixture,wherein the determination portion determines as to whether the pile hasbeen cut or not, based on ranges of the sound data and vibration storedin the DB, and the control portion moves the nozzle housing in acircumferential direction up to a set angle by driving the rotation unitwhen the determination portion determines that the pile has beenpenetrated by a waterjet.
 8. A method for cutting a pile through anon-contact type pile cutting apparatus using a waterjet comprisingsteps of: putting a pile cutting apparatus into an inside of a pilethrough a putting apparatus; fixing the pile cutting apparatus to theinside of the pile by operating a gripper unit by a control portion whenthe pile cutting apparatus has reached a cutting position of the pile;setting a waterjet to move a waterjet unit provided at one side of abody toward an inner surface of the pile through a nozzle driving unit;feeding an abrasive mixture in which a fluid and an abrasive of a setratio are mixed, to a feed line with the waterjet unit from the outsideby a feed unit, and spraying the abrasive mixture toward the pile in ahigh pressure from a nozzle portion of the waterjet unit, which isconnected to the fee line; and cutting the pile by rotating the waterjetunit around a central axis of the body by a rotation unit.